Mixing oil???

[fcremc]

I am wondering is there any harm in mixing Mobil 1 Full Synthetic with some Mobil 1 Full Synthetic Extended Performance? Some thing with Castrol Synthetic & Castrol Synthetic Extended Performance. My limited knowledge tells me no harm but I thought I'd better get a more informed opinion.

Thank you,
Fred

 

[Eddie]

I see no issues here with any of the combinations. Ed

 

[newtoncd8]

I mix conventional Pennzoil with Pennzoil Platinum on my daily drivers, no problems.

Here is Mobil's official answer:
"Mobil 1 is fully compatible with conventional motor oils, semi-synthetic motor oils and other synthetic motor oils, should it be necessary to mix them. But the superior performance of Mobil 1 will be reduced by diluting it."

 

[beanoil]

Blend on. My next change will be Mobil 1 15w50 and Mobil Super 5w20. I used the Widman viscosity calculator to find the right ratio for a typical 10w30, (5 quarts 5w20 to 3 of the 15w50).

 

[crazyoildude]

I wrote about this before...A friend of mine that owns a repair shop takes all the quarts and lets them drain into a large jug he uses peak, Smittys Super S, Gulf and anything else he gets cheap even synthetics...It all goes into one big container and he uses that for all his personal vehicles his belief is oil is oil and there is no changing his mind...lol
His vehicles all seem to run good except for one subaru that needed a head gasket at 55,000 miles but that is common with Subarus and had nothing to do with oil.

 

[Shrubitup]

Originally Posted By: crazyoildude

His vehicles all seem to run good except for one subaru that needed a head gasket at 55,000 miles but that is common with Subarus and had nothing to do with oil.


guy at work bought a new 2016 Subaru and purchased a 100K mile extended warranty to cover the head gasket and oil usage issues common with Subaru. Doesn't make sense to me to purchase from these folks who can't engineer these problems out of their cars.

 

[demarpaint]

Originally Posted By: Curtis Newton
I mix conventional Pennzoil with Pennzoil Platinum on my daily drivers, no problems.

Here is Mobil's official answer:
"Mobil 1 is fully compatible with conventional motor oils, semi-synthetic motor oils and other synthetic motor oils, should it be necessary to mix them. But the superior performance of Mobil 1 will be reduced by diluting it."


That sums it up nicely. This topic has been discussed many times before. The oils can be mixed. The end product however is unknown and will not be guaranteed by Mobil. That's more or less what they told me on the phone.

 

[MrQuackers]

So if you do not use Mobil every oil change, the warranty is null & void? There is significant residual oil when you change the oil.

 

[dparm]

Originally Posted By: fcremc
I am wondering is there any harm in mixing Mobil 1 Full Synthetic with some Mobil 1 Full Synthetic Extended Performance? Some thing with Castrol Synthetic & Castrol Synthetic Extended Performance. My limited knowledge tells me no harm but I thought I'd better get a more informed opinion.

Thank you,
Fred



If both oils are API-certified, they must be mixable.

 

[OVERKILL]

Originally Posted By: dparm
Originally Posted By: fcremc
I am wondering is there any harm in mixing Mobil 1 Full Synthetic with some Mobil 1 Full Synthetic Extended Performance? Some thing with Castrol Synthetic & Castrol Synthetic Extended Performance. My limited knowledge tells me no harm but I thought I'd better get a more informed opinion.

Thank you,
Fred



If both oils are API-certified, they must be mixable.


While this is true, the end product is not guaranteed to have the same level of performance as either of the products by themselves.

 

[wemay]

http://www.machinerylubrication.com/Read/911/lubricant-incompatibility

https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=115203

 

[Bud]

I have been mixing oils all my life. Talk about living on the edge.

 

[Shrubitup]

Originally Posted By: Bud
I have been mixing oils all my life. Talk about living on the edge.


Careful, dude.

 

[53' Stude]

What gets me is that a few years ago on here people were making their own "CATERHAM Blend" with TGMO 0w20/Mobil 1 0w40 and even Mobil 1 Advanced Fuel Economy 0w20/Mobil 1 0w40. Obviously nothing blew up

 

[wemay]

I think a cautionary recommendation that additives may clash is a good distance away from the legitamization of mixing because it's never blown an engine up. Everyone agrees that any issue would be extremely rare.

 

[cmhj]

People worry too much

 

[wemay]

Originally Posted By: cmhj
People worry too much


In the grand scheme of things, yes.

 

[Garak]

Originally Posted By: MrQuackers
So if you do not use Mobil every oil change, the warranty is null & void? There is significant residual oil when you change the oil.

To a point, you're right. Mobil's warranty specifically excludes damage that was caused by another product. Obviously, they have to cover their own behinds, but it's also useful for product loyalty.

Heck, I prefer to use the same batch number from oil change to oil change, but I'm nuts.

 

[Stewie]

There is nothing wrong with mixing them.

They are not explosives